CHAPTER 11: METERING METERED VALUES
D90
PLUS
LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL 563
The following voltages and currents are measured for wye-connected instrument
transformers in the ACB phase rotation:
Eq. 57
Eq. 58
Eq. 59
The following voltages and currents are measured for delta-connected instrument
transformers in the ABC phase rotation. The zero-sequence voltage (V_0) is not measurable
under the delta connection of instrument transformers and is defaulted to zero.
Eq. 60
Eq. 61
The following voltages and currents are measured for delta-connected instrument
transformers in the ACB phase rotation. The zero-sequence voltage (V_0) is not measurable
under the delta connection of instrument transformers and is defaulted to zero.
Eq. 62
Eq. 63
In these equations, a represents phase rotation operator that rotates a phasor vector
forward by 120° (a = 1∠120°).
As an example, consider a wye connected VT with the following system voltages (in
secondary volts): V
AG
= 13.9 V∠0°, V
BG
= 76.2 V∠–125°, V
CG
= 79.7 V∠–250°, V
AB
= 84.9 V∠–
313°, V
BC
= 138.3 V∠–97°, and V
CA
= 85.4 V∠–241°. For simplicity, the power system
voltages are phase-referenced to V
AG
. However, any value can be chosen as a reference. It
is important to remember that displayed values are always referenced as to the voltage
specified by the
Frequency and Phase Reference setting.
Eq. 64
Eq. 65
Eq. 66
As another example, consider a delta connected VT with the following system voltages (in
secondary volts): V
AB
= 84.9 V∠0°, V
BC
= 138.3 V∠–144°, and V
CA
= 85.4 V∠–288°. For
simplicity, the power system voltages are phase-referenced to V
AB
. However, any value
B,
B9
&%$&*%*$*
,,,999
B,
B9
&%$&*%*$*
D,,D,D99D9
B,
B9
&%$&*%*$*
,DD,,9DD99
B,
B9
&%$&$%&$%
,DD,,9DD99
B,
B9
&%$&$%&$%
D,,D,D99D9
B,
B9
&%$&$%&$%
D,,D,D99D9
B,
B9
&%$&$%&$%
,DD,,9DD99
² ²
B9
&*%*$*
999
B9
&*%*$*
9DD99
B9
&*%*$*
D99D9
To Next Page
Loading...
